ICMP 21. My system is configured in such a way to respond for ICMP broadcast and multicast requests from outside our network. Compare the IP address reported by DNS or NetBIOS in the network trace for the server with the IP addresses you noted earlier. the traceroute Command on Operating Systems . I am observing a temporary not reply to icmp request on different switches 1920. As mentioned in the previous page, an Echo is simply what we networking engineers call a 'ping'.The Echo Reply is, as most would guess, the 'ping reply'.ICMP Echos are used mostly for troubleshooting. ICMP协议中ping命令no response seen？-CSDN社区 Note: Enabling any debug commands on a production router may cause serious problems. The BIG-IP system uses this status to control the way that the system manages responses to any ICMP echo requests sent to the virtual address. Remove all added blocks for ICMP requests: ~]# firewall-cmd --remove-icmp-block=